Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study performed to GLP and guideline

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
GLP compliance:
yes (incl. certificate)
Test type:
fixed concentration procedure
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Calcium sulfate, dihydrate
- Substance type: White powder
- Physical state: Solid
- Storage condition of test material: Room temperature in the dark

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan UK, Ltd, Oxon, UK
- Age at study initiation: 8-12 weeks
- Weight at study initiation: 199 - 350g
- Fasting period before study:
- Housing: Housed in groups of five by sex in solid-floor polypropylene cages with stainless steel lids, furnished with softwood flakes
- Diet: Harlan 2014 rodent diet ad libitum
- Water: ad libitum



ENVIRONMENTAL CONDITIONS
- Temperature: 19-25 °C
- Humidity: 30 -70 %:
- Air changes: 15 changes per hr
- Photoperiod: 12 hrs dark / 12 hrs light


Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
nose only
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure chamber volume: Volume of ~ 30L (dimensions: 28 cm diameter x 50 cm high)
- Method of holding animals in test chamber: Each rat was held in a tapered, polycarbonate restraining tube fitted with a single tier of the exposure chamber and sealed by means of a rubber 'O' ring
- Source and rate of air: Compressed air was supplied by means of an oil free compressor
- Method of conditioning air: Passed through a water trap and respiratory quality filters
- System of generating particulates/aerosols: SAG 410 Solid Aerosol Generator (TOPAS GmbH, Dresden Germany)
- Method of particle size determination: Determined three times during the exposure period using a Marple Personal Cascade Impactor )Westech IS Ltd, Beds, UK)


TEST ATMOSPHERE
- Brief description of analytical method used: Gravimetric method
- Samples taken from breathing zone: yes




Analytical verification of test atmosphere concentrations:
no
Duration of exposure:
4 h
Concentrations:
Mean achieved 3.26 mg/L (calcium sulfate dihydrate), equivalent to >2.61 mg/L calcium sulfate anhydrous
No. of animals per sex per dose:
5/sex/dose
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: All animals were observed for clinical signs at hourly intervals during exposure, immediately on removal from the restraining tubes at the end of exposure, one hour after termination of exposure and subsequently once daily for fourteen days.
- Necropsy of survivors performed: yes

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 3.26 mg/L air (nominal)
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: Equivalent to > 2.61 mg/L calcium sulfate anhydrous
Mortality:
No deaths occurred
Clinical signs:
Common abnormalities noted during the study included increased respiratory rate, hunched posture, pilo-erection and wet fur. Animals recovered quickly to appear normal from Day 2 post-exposure

Body weight:
One male animal exhibited a reduced bodyweight gain during Week 1 but recovered to show normal development during Week 2. Normal bodyweight development was noted for all other animals during the course of the study.

Gross pathology:
With the exception of one instance of dark patches on the lungs, no macroscopic abnormalities were detected at necropsy

Any other information on results incl. tables

Table 1: Temperature and relative humidity in exposure temperature:

Time (minutes)

Chamber temperature (°C) during exposure

Chamber relative humidity (%) during exposure

0

21

58

30

21

57

60

21

56

90

21

52

120

21

56

150

21

55

180

21

57

210

21

56

240

21

57

Table 2: Air flow and oxygen concentration in exposure chamber

Time (minutes)

Air flow (L/min) during exposure

Chamber relative humidity (%) during exposure

-3

50

-

0

50

20.8

30

50

-

60

50

-

90

50

-

120

50

20.8

150

50

-

180

50

-

210

50

-

240

50

20.8

Table 3: Exposure chamber atmosphere concentrations

Duration of exposure (minutes)

Net weight of sample (mg)

Volume of air sampled (L)

Chamber flow rate (L/min)

Atmosphere concentration (mg/L)

5

5.45

2

50

2.73

16

6.02

2

50

3.01

30

7.33

2

50

3.67

46

5.04

2

50

2.52

60

5.77

2

50

2.89

75

6.56

2

50

3.28

88

6.26

2

50

3.13

105

7.37

2

50

3.69

120

6.00

2

50

3.00

135

5.13

2

50

2.57

150

6.00

2

50

3.00

166

7.18

2

50

3.59

180

7.21

2

50

3.61

195

7.65

2

50

3.83

210

7.73

2

50

3.87

225

7.74

2

50

3.87

237

6.16

2

50

3.08

Mean achieved atmosphere concentration (mg/L) = 3.26

Standard deviation = 0.46

Nominal concentration:

Test material use (g)

150

Air flow (L/min)

50

Total generation time (mins)

243

Nominal concentration (mg/L)

21.3

Table 4: Cascade impactor data

Impactor stage number

Cut point (µm)

Amount collected (mg) per sample

Mean amount collected (mg)

1

2

3

3

9.0

0.02

0.14

0.08

0.08

4

6.3

0.24

0.61

0.29

0.38

5

4.0

0.48

0.92

0.55

0.65

6

1.7

0.28

0.51

0.32

0.37

7

0.81

0.20

0.28

0.27

0.25

8

0.30

0.03

0.09

0.11

0.08

Back up filter

<0.30

0.03

0.10

0.03

0.05

Total mean amount of test material collected

1.86

Table 5: Calculation

Cut point (µm)

Log10 Cut point

Mean cumulative amount less than cut point

(mg)

%

Probit

9.0

0.954

1.78

95.7

6.72

6.3

0.799

1.40

75.3

5.68

4.0

0.602

0.75

40.3

4.76

1.7

0.230

0.38

20.4

4.17

0.81

-0.092

0.13

6.99

3.52

0.30

-0.523

0.05

2.69

3.07

Results:

Mean mass median aerodynamic diameter (MMAD) = 2.92 µM

Geometric standard deviation (GSD) = 2.49

Predicted amount less than 4 µm = 63.6%

It is recognised that the mean achieved atmosphere concentration is lower than would generally be acceptable for this type of study. During characterisation, changes were made to the generation system to increase the inhalable portion of the test material, however, these changes also reduced the achievable test atmosphere concentration. However, as these changes reduced the particle size significantly it made it such that even at reduced test atmosphere concentrations the animals would be exposed to higher concentrations of particles <4 μm than if they were to be exposed to the standard target concentration of 5mg/L. It was, therefore, preferable to expose the animals to a lower concentration of test material, as this resulted in the animals being exposed to the highest possible concentration of particles <4μm.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Remarks:
Criteria used for interpretation of results: EU
Conclusions:
The acute inhalation median lethal concentration (4 hr LC50) of Calcium sulfate dihydrate, in the HsdHanTM : WIST strain rat, was greater than 3.26 mg/L, the equivalent LC50 value for the anhydrous form of this material is considered to be >2.61mg/L. On the basis of this result, Calcium sulfate dihydrate does not meet the criteria for classification in the EU in accordance with both Council Directive 67/548/EEC as amended and Regulation (EC) No 1272/2008 and will not require labelling for inhalation toxicity.